1. Field of the Invention
The present invention relates to a lubricant-holding base material, a method for producing the same, a lubricating material, and a method for producing the same.
2. Description of the Related Art
A material holding a fluorine-based lubricant in recess portions of an uneven structure body in which fine protrusions and recesses are formed on the surface has been proposed (Wong, Tak-Sing, et al. “Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity.”, Nature 477. 7365 (2011), p. 443-447). This material is slippery enough to allow liquid droplets to slip on the surface on which the lubricant is exposed through openings in the fine recess portions, and thus the surface is called a slippery liquid-infused porous surface (SLIPS). This material is a non-woven fabric formed of a fiber formed of a compound including fluorine in the structure.
Meanwhile, as the uneven structure body in which fine protrusions and recesses are formed on the surface, there is a honeycomb-structure film or a pillar-structure film. The honeycomb-structure film refers to a film that is provided with a honeycomb structure by arranging a plurality of pores as fine recess portions on a film surface. In addition, the pillar-structure film refers to a film in which protrusion portions are formed in a fine columnar pillar shape.
The honeycomb-structure film can be produced using a dew condensation method (also referred to as a breath figure method) (for example, refer to JP2009-293019A). The dew condensation method is a method in which a solution including a hydrophobic polymer for forming a honeycomb film as a raw material is cast so as to form a cast film, dew is condensed on this cast film so as to form water droplets, and a solvent and water droplets are evaporated, thereby producing a honeycomb-structure film (for example, refer to JP2009-293019A). According to this dew condensation method, the water droplets act as casting molds for pores, and thus it is possible to obtain a honeycomb-structure film in which a plurality of extremely fine and uniform pores are formed in a state of being regularly arranged.
In addition, the pillar-structure film can be produced using the honeycomb-structure film. As a method for producing the pillar-structure film using the honeycomb-structure film, there is a method in which an adhesive film including an adhesive on the surface is attached to one film surface of a honeycomb-structure film on which pores are formed and the adhesive film is drawn, thereby peeling a portion in the above-described film surface side in which pores are formed off from a portion on the other film surface side. In this method, the portion on the other film surface side becomes the pillar-structure film (for example, refer to JP2009-293019A). In addition, a method for producing a pillar-structure film by irradiating a honeycomb-structure film with ultrasonic waves also has been proposed (for example, WO2004/048064A). According to this method, it is possible to easily produce a pillar-structure film using a honeycomb-structure film.
Furthermore, the honeycomb-structure film can also be formed on a curved surface. For example, as a method for forming a honeycomb-structure film on the outer circumferential surface and the inner circumferential surface of a cylinder, there is a method in which the cylinder is immersed in the above-described solution including a hydrophobic polymer as a raw material, a lubricating gas is supplied to the outer circumference and the hollow portion of the cylinder, and then a dried gas is supplied (for example, refer to JP2010-229373A).